Pre-heating the electrodes prior to ignition of a gas discharge lamp is performed for preventing excessive deterioration of said electrodes. A known method for pre-heating electrodes is switching a current through the electrodes which may be series connected for that purpose. This switching may be done under control of an electrical circuit. Devices for controlling a gas discharge lamp are often referred to as a “starter” in the art. In fact, starters comprising electrical circuit, comprising e.g. a microcontroller, may also be applied for controlling the lamp after the starting phase, for controlling voltages, currents, frequencies and waveforms of the lamp. These electrical circuits may require a low DC voltage power supply, e.g. of 5 to 24 Volts, which may be retrieved from a mains voltage, or—for reasons of availability of a limited number of terminals in a standard lamp housing, from a lamp voltage. For that purpose, the control circuit may be connected in series with the lamp electrodes during starting of the lamp. In such configuration, for enabling a pre-heating current to flow through the lamp electrodes, it may be necessary to shortcircuit the terminals of the control circuit. A power source is then needed to power at least the electrical circuit during the pre-heating period.
When considering the use of a charged capacitor as a power source, a capacitor that can store enough power for an average intelligent building block to bridge an average pre-heating period appears to require such large physical dimensions that it cannot be integrated in a commonly applied control circuit housing. Also attempts to reduce the power absorbed by an intelligent building block by switching at least a microcontroller thereof to very low energy consumption or by switching off peripherals have not lead to a working solution.